Air leak, Honeywell Valve

[neilleeds]

Hi,

I am having a problem with air in my open-vented central heating system. I checked out the Honeywell mid-pos valve and it appeared to have been weeping so I guess it is this that is introducing air. Having tightened the nuts a bit it doesn't appear to be weeping now but it seems like air is still getting in the system.

The symptons are:

Slight bubble occasionally in radiators, usually when boiler turns off and pump stays on, also on cold startup.

When valve moves to HW mode there is an audible and random clicking noise which sounds like air bubbles through valve (valve is quiet on CH mode).


1. The valve is after the pump, could this still introduce air (seen references to it when on the low-pressure side)?

2. If it doesn't appear to be leaking water, could it still be introducing air?

3. Is it likely the air is coming from somewhere else? There was sludge in the header tank at one point but I have removed it and it has stayed clean.

Many thanks to anyone who can help.

Neil

 

[gavdac]

One thing to try is to join the feed and expansion this way there is no open air vent it won't hurt anything so you have nothing to lose.

Some times there are small problems like this with no definate answer.

Good luck

 

[SPC]

if there was a fault on the boiler causing excessive temperatures and the feed and vent is linked into each other could spell disaster!! wouldnt have thought the weeping joing would be introducing air. you can get micro leaks which let air in and can be dependant on where the pump is fitted in situ with the feed and vent pipe, ie whether the system is under positive or negetive pressure.

one of the easier things to try might be fitting an auto air vent too the system at a high point in the cylinder cupboard see if that cures your problem before delving any deeper

 

[danielp]

yer but theres still a vent regardless of if there joined together, what speed is the pump on? try turning that down.

 

[SPC]

ahhh just reread the post, for some reason i was thinking join feed and vent together. the majority of the time the feed and expansion are the same pipe. or am i missing something blatently simple here

 

[neilleeds]

Thanks for everyone's help, I have ruled out the divertor valve. the clicking was from the pump valve, I tracked it down using a screwdriver as a stethoscope which I read somewhere! It worked! The reason it clicked on HW and not CH I guess was because of less resistance on the HW circuit, opening the valve a little more stopped the clicking.

There is still air coming from somewhere though, I suspect the lockshield valves. Several appear to be leaking, when I take the cap off it is wet inside the cap (could this be condensation?). I am going to try fixing with PTFE as I have read in various places.

 

[neilleeds]

In terms of an AAV, at the moment I have a vertical pipe from the pump to the Honeywell valve, from here the pipes go left for HW and right for CH. There is a manual air vent on the left (HW) pipe but nothing on the right. Should there be one (or an AAV) on the CH pipe as well?

Our bedroom rad glugs quite a bit on a morning when the system fires up from cold. I guess there are two possible reasons:

1. Cold components are letting in air somewhere
2. Air in system is collecting overnight and then pushed through in morning.

Again thanks for your help.

 

[neilleeds]

For anyone interested, it appears that the boiler has been kettling, causing the air. Turning the boiler stat down and pump up seems to have helped. I'm planning on putting some X400 in for around a month and then a good flush followed by X100 and maybe X200. Hopefully this will restore the system to full health.

Thanks for everyones help.

 

[WHPES]

Converting to sealed system removes any chance of ar getting sucked in.

 

[Blackcatgas]

You might have a leak under the floor